Fix build with ToT libc++

system/vold/fs/F2fs.h:33:28: error: no template named 'vector' in namespace 'std'
   33 |                 const std::vector<std::string>& user_devices);
      |

Test: Build with ToT libc++
Change-Id: Iab5f3fc06ce780ae81e96df7fd091a28407c1422
diff --git a/fs/F2fs.h b/fs/F2fs.h
index 7192b54..a0218f2 100644
--- a/fs/F2fs.h
+++ b/fs/F2fs.h
@@ -20,6 +20,7 @@
 #include <utils/Errors.h>
 
 #include <string>
+#include <vector>
 
 namespace android {
 namespace vold {